It depends if there's anything else you need more
Becuase I mean, a 17" monitor works after all.
I'm using one.
But if you can spend the $200 on something better, like say.. more ram or something.. go for that instead :]
But if they money is burning a hole in your pocket, and your current monitor aggrivates you to death, go for it :>
I went from a 17" CRT to a 19" LCD and was blown away. It's not going to be as big of a difference for you, cause you're starting with an LCD but, go for it, it'll make a world of difference.
I used to use a 17CTR on my old build and now I have a dell 20.1 wide and it is so much better. it gives u so much more space, i can comfortably have like Internet Explorer, TV, and IM going simotaniously. i would really suggest it if you like space and big screens, even a 19 inch is good too.
Get a 19" and add it in addition to your 17"...that's what I'm doing...my primary monitor is a Samsung 17", my secondary monitor is a HannsG 19" widescreen.